| Electrospinning and solid state polymerization: A simple and versatile route to conducting PEDOT composite films | |
| Pisuchpen T., Keaw-on N., Kitikulvarakorn K., Kusonsong S., Sritana-anant Y., Supaphol P., Hoven V.P. | |
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| Conducting polymer composite films containing poly(3,4-ethylenedioxythiophene) (PEDOT) was prepared by solid state polymerization (SSP) of 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) in the matrices of polystyrene (PS), sulfonated polystyrene (SPS), or poly(methyl methacrylate) (PMMA). A thin fiber mat was first fabricated by electrospinning a mixed solution of the polymer matrix and DBEDOT on glass slides. The SSP of the DBEDOT embedded in the polymer matrix was then induced by heating at 60–80 °C, which resulted in a dark blue PEDOT composite film, structurally confirmed by Raman spectroscopy and X-ray diffraction spectroscopy. It was found that compression during heating produced better dispersed PEDOT particles in the polymer matrix. The conductivity of the composite fiber was found to reach as high as approximately 13, 14 and 32 S/cm for the PEDOT/PS, PEDOT/SPS and PEDOT/PMMA composite films, respectively. These conductivity values are comparable to that of the pure PEDOT generated directly by SSP in the absence of a polymer matrix. © 2017 Elsevier Ltd | |
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| Acrylic monomers; Conducting polymers; Electrospinning; Esters; Polymer films; Polymer matrix; Polymer matrix composites; Polymerization; Polystyrenes; 2 ,5-dibromo-3 ,4-ethylenedioxythiophene; Conducting polymer composites; PEDOT; Poly(3 ,4 ethylenedioxythiophene) (PEDOT); Poly(methyl methacrylate) (PMMA); Solid state polymerization; Sulfonated polystyrene; X-ray diffraction spectroscopy; Composite films | |
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| Effect of type and content of tackifier on adhesion of natural rubber and reclaimed natural rubber based sealant | |
| Raethong P., Boonkerd K. | |
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| Adhesion property of natural rubber (NR) and reclaimed natural rubber (RNR) based sealant with concrete was studied here. The effect of tackifier type and loading on the tensile properties of the rubber based sealant sandwished between two flat cements was evaluated. There are three different tackifiers including Coumarone-indene resin (CI), petro resin (PE) and gum rosin (GR). The result initially showed that at the 20 phr of tackifier both NR and RNR sealant mixed with CI consumed the highest force to separate the rubber based sealant from the concrete. This might be due to the highest compatiblility between CI and rubber. Regardless of the tackifier type, all NR based sealants showed the cohesive failure while all RNR based sealants only showed the adhesive failure. Moreover, the NR based sealant seemed to be stronger than the RNR based one. When considering the effect of CI loading on the adhesion, it was shown that for both NR and RNR based sealents, the highest stress was observed when the rubber based sealant loaded with the 20 phr of CI. © Published under licence by IOP Publishing Ltd. | |
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| Adhesion; Concretes; Resins; Sealants; Stress analysis; Adhesion properties; Adhesive failure; Cohesive failures; Tackifiers; Rubber | |
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| Effects of KF Loading on Mg–Al Mixed Oxides for the Selective Synthesis of Trimethylolpropane Triesters | |
| Katekong S., Butnark S., Ngamcharussrivichai C. | |
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| A series of Mg–Al hydrotalcites (HTCs) calcined at different temperatures were evaluated for their suitability as solid base catalysts for the selective synthesis of trimethylolpropane triesters (TMPTEs) via transesterification of trimethylolpropane (TMP) with a mixture of C8–C10 fatty acid methyl esters (FAMEs). The effect of potassium fluoride (KF) loading of the calcined HTCs on the physicochemical and catalytic properties of the materials attained was ascertained. Using a 5 wt% catalyst loading and a FAME:TMP molar ratio of 3.5:1 at 170°C for 8 h, the Mg–Al mixed oxide obtained by calcining HTC at 500°C (HTC-500) gave the highest TMPTE selectivity and FAME conversion. Impregnating HTC-500 with 10 wt% KF (KF/HTC-500) generated strongly basic KMgF3, KOH, K2O, and coordinatively unsaturated F− sites. The FAME conversion and TMPTE yield obtained over different HTC and KF/HTC-500 catalysts depended on their total basicity, where a basic strength of 15 < H_ < 18.4 was required for optimal TMPTE selectivity. The KF/HTC-500 calcined at 500°C was the most suitable catalyst and showed a superior performance to NaOCH3, a common homogeneous base for the polyol ester production. © 2017, Copyright © Taylor & Francis Group, LLC. | |
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| Alkalinity; Aluminum; Calcination; Catalyst selectivity; Catalysts; Esters; Fatty acids; Thermomechanical pulping process; Transesterification; Al hydrotalcite; Catalytic properties; Co-ordinatively unsaturated; Fatty acid methyl ester; Fatty acid methyl esters (FAMEs); Selective synthesis; Solid base catalysts; Trimethylolpropane; Loading | |
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| Structure-property relationship of π-extended boron-dipyrromethene derivatives towards optoelectronic applications | |
| Songkhao J., Banerjee R., Debnath S., Narasimhan S., Wannaprom N., Vanalabhpatana P., Seriani N., Gebauer R., Thamyongkit P. | |
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| A series of novel boron-dipyrromethenes bearing β-benzo-fused rings, or benzo-BODIPYs, and phenyl, thienyl and bithiophenyl meso-substituents was synthesized, and investigated for their photophysical and electrochemical properties. Results from the UV–visible spectrophotometry revealed that the boron-complexation and the presence of the β-benzo-fused rings significantly increase absorptivity of the molecules in the longer wavelength region. Moreover, according to the observed electrochemical and photophyscial properties of these compounds, the extended conjugation system and the presence of thiophene-based meso-substituents in the target benzo-BODIPYs created great impact on the energy levels of the molecular frontier orbitals, resulting in narrowing of the energy gap of the materials. We have also demonstrated the use of density functional theory calculations to evaluate the performance of these compounds as dye sensitizers in solar cells. While all the molecules studied have their frontier orbitals aligned appropriately with respect to the band gap of TiO2, they are found to differ in their charge injection properties when anchored on TiO2, and even more markedly in electron-hole separation and change in dipole moment upon excitation. Upon combining these criteria using a simple model and the experimental results, the bithiophenyl-substituted benzo-BODIPY was suggested as the optimal candidate. © 2017 Elsevier Ltd | |
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| Boron; Dies; Electron injection; Energy gap; Molecules; Titanium dioxide; Benzo-BODIPY; BODIPY; Boron dipyrromethene; Electron-hole separation; Optoelectronic applications; Photophyscial property; Structure property relationships; Visible spectrophotometries; Density functional theory; Boron; Energy | |
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| Self-healing hybrid nanocomposite anticorrosive coating from epoxy/modified nanosilica/perfluorooctyl triethoxysilane | |
| Kongparakul S., Kornprasert S., Suriya P., Le D., Samart C., Chantarasiri N., Prasassarakich P., Guan G. | |
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| Self-healing hybrid nanocomposite was successfully prepared from epoxy resin containing self-healing microcapsules and organosilane modified nanosilica to enhance the anticorrosion performance of an epoxy coating. Nanosilica surface was modified with (3-glycidoxypropyl)trimethoxysilane (GPTMS) and (3-aminopropyl)trimethoxysilane (APTES) to accomplish well dispersion in the polymer matrix. Perfluorooctyl triethoxysilane (POT), ethanolamine (ETA), and diethanolamine (DEA) as self-healing agents were encapsulated by polymer shell and incorporated into the epoxy coating along with modified nanosilica to form anticorrosion barrier of organic and inorganic coating on a cold-rolled steel surface (CRS). The results revealed that the self-healing hybrid nanocomposite containing 3 wt% of GPTMS-modified silica (GMS) and 10 wt%POT microcapsules possessed the best corrosion performance with the corrosion rate of 0.09 mm/year (Icorr of 0.01 mA/cm2), corrosion rating number of 9 and oxygen permeability about 0.14 barrer. The addition of modified silica (GMS) and self-healing agent microcapsules (POT) effectively increased the length of the diffusion pathways, as well as decreased the O2 permeability of the nanocomposite film. © 2016 Elsevier B.V. | |
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| Coatings; Cold rolling; Corrosion; Corrosion protection; Corrosion rate; Corrosion resistance; Encapsulation; Ethanolamines; Films; Metal cladding; Microstructure; Nanocomposite films; Nanocomposites; Organic coatings; Plastic coatings; Silanes; Silica; Steel sheet; Anti-corrosion; Anti-corrosive coatings; Anticorrosion performance; Corrosion performance; Epoxy coatings; Hybrid nanocomposites; Oxygen permeability; Self-healing; Epoxy resins | |
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| Morphology, mechanical and thermal properties of poly(lactic acid) (PLA)/natural rubber (NR) blends compatibilized by NR-graft-PLA | |
| Sookprasert P., Hinchiranan N. | |
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| Natural rubber (NR) is expected to enhance impact strength of poly(lactic acid) (PLA). Because the polarity difference of NR and PLA leads PLA/NR blends having phase separation and poor mechanical properties, this research aimed to synthesize NR-graft-PLA (NR-PLA) via esterification of maleated NR (NR-MAH) with PLA. The role of NR-PLA used as a compatibilizer on mechanical and thermal properties of the PLA/NR blends was studied. Maximum grafted PLA level at 66.8% (w/w) was reached when NR-MAH was esterified with PLA [2/1 (w/w) PLA/NR-MAH] catalyzed by 0.05 M 4-dimethylaminopyridine at 140 °C. The addition of 5% (w/w) NR-PLA [36.6% (w/w) grafted PLA content] into PLA/NR blend [80/20 (w/w)] increased Izod impact strength of the neat PLA plate from 28.9 J/m to 62.7 J/m due to partial miscibility of blends attested by morphology analysis and Molau test. Hydrolytic degradation of PLA/NR blends with and without the addition of NR-PLA was also examined. © Materials Research Society 2017. | |
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| Blending; Chemical reactions; Esters; Impact strength; Lactic acid; Phase separation; Polymers; Rubber; Thermodynamic properties; 4-dimethylaminopyridine; compatibility; Graft co polymerizations; Hydrolytic degradation; Izod impact strength; Mechanical and thermal properties; Morphology analysis; Poly lactic acid; Grafting (chemical) | |
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